1. Field of the Invention
The present invention relates to a novel aromatic polyester carbonate, more particularly to an aromatic polyester carbonate having a good melt moldability and able to provide a molded product having excellent physical properties, and having liquid crystal properties, and to a process for producing the same.
2. Description of the Related Art
Recent technical advances in various fields of industry, and energy saving policies conducted in an effort to conserve energy resources have led to a demand for higher performance and lighter weight organic polymeric materials.
Further, there is a demand for higher performance materials which can be used as metal alternatives. To meet these demands for higher performance plastics, polymers having excellent mechanical properties such as optically anisotropic liquid crystal polymers characterized by parallel arrangements of molecular chains are under research. Representative of such liquid crystals is a wholly aromatic polyester but, for example, poly (p-oxybenzoate) "EKONOL", which is its copolymer, have too high melting points, and therefore, melt molding is impossible or very difficult.
German Patent No. 2704315 discloses a thermotropic wholly aromatic polyester carbonate based on p-hydroxybenzoic acid, carbonic acid, hydroquinone and, if desired, an aromatic dicarboxylic acid. These polyester carbonates have a flow temperature of at least 265.degree. C, but the melt viscosity is too high and melt molding is difficult.
Furthermore, Japanese Unexamined Patent Publication (Kokai) No. 60-38427 discloses a thermotropic wholly aromatic polyester carbonate based on p-hydroxybenzoic acid, carbonic acid, diphenol, 4,4'-dihydroxydiphenyl as diphenol and, if desired, an aromatic dicarboxylic acid. In Examples of the above published patent specification, only an aromatic polyester carbonate using hydroquinone as the diphenol component is disclosed, but the moldable temperature range of the aromatic polyester carbonate obtained was 260.degree. C. or higher, and thus the polyester carbonate has an unsatisfactory moldability. Further, in the above published patent specification, although a large number of diphenols are shown as examples of the diphenol component, ##STR4## wherein X represents an substituted or non-substituted phenyl group, an alkyl group having 3 to 6 carbon atoms or a halogen, an Example using these monomers as the diphenol unit is not disclosed, and thus the effect gained by using these monomers is not clear.
Further, among monomers represented by the general formulae: ##STR5## wherein X.sup.3 are the same or different and represent an alkyl group, phenyl group, or a halogen, and m is an integer of 0 to 4, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl benzophenone, 4,4'-dihydroxydiphenyl methane, resorcinol, 2,7-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 2,3-dihydroxynaphthalene are exemplified. But, an Example using these monomers as the diphenol unit is not disclosed and the effect gained by using these monomers is not clear.
On the other hand, a polyester carbonate comprising structural units represented by the formulae: ##STR6## wherein R may be the same or different and represents an alkyl group, phenyl group or a halogen, and n is an integer of 0 to 4, ##STR7## is disclosed in, for example, a Comparative example of Japanese Unexamined Patent Publication (Kokai) No. 62-70417, but since the polymerization reaction is completed at a temperature of 300.degree. C. and under a pressure of 1 mmHg, the resultant polymer has a reduced viscosity [.eta.sp/C] of a solution at a 0.2 g/dl concentration in p-chlorophenol as the solvent at 60.degree. C, of as low as 0.52 dl/g, and accordingly, the mechanical properties thereof are not satisfactory. Further, the above specification does not disclose the liquid crystal property of the polyester carbonate shown by the previous general formulae.